DESCRIPTION (adapted from the applicant's abstract and specific aims): The possible structural or functional role that the high mobility group (HMG) proteins 1,2 and E play in transcription will be examined. By using the anticancer drug and chemical cross-linking agent, cis-diamminedichloroplatinum (II) (cisplatin or DDP), which preferentially cross-links the HMG 1,2 and E proteins to DNA in chromatin, a unique route is available to determine if these proteins play a structural role in molding either transcriptionally active or inactive regions within the bulk of higher-order structure of chromatin. The Specific Aims are: (1) Using cis-diamminedichloroplatinum (II) as a selective cross-linking agent and specific polyclonal antibodies to the HMG proteins 1,2 and E, determine whether the HMG proteins are preferentially interacting with transcriptionally active or inactive sequences within the nucleus. (2) Use restriction endonuclease digestion to determine if transcriptionally active genes are preferentially accessible (limited digestion) within chromatin. Alternatively, carry out a limited digestion on intact nuclei to determine if the transcriptionally active sequences are associated with the nuclear matrix DNA. This restriction procedure will also be used following treatment of nuclei with various levels of cisplatin to determine if the HMG proteins are preferentially cross-linked to the excised or pelleted sequences. In objectives 1 and 2, erythrocyte nuclei from 11-day embryos obtained from blood, isolated with and without histone deacetylase inhibitor, will be compared to determine the influence of acetylation on HMG interaction in chromatin structure. The transcriptionally inactive erythrocytes from adult chickens will also be examined to further determine if the interactions (and therefore the possible role) of HMG proteins 1,2 and E change during development. (3) Using polyclonal antibodies to the HMG proteins, preliminary in vitro transcriptional assays will be carried out with nuclei from 11-day embryos to determine whether the HMG proteins are associated with the transcription complex. Different levels of alpha-amanitin will be incorporated in the assay to distinguish whether the HMG proteins exhibit any preferential effect on transcription by RNA polymerase I, II or III.